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Title: Challenging Cooperation: Inequality, Global Commons, Future Generations
Abstract: Cooperation is abundant in the world around us, spanning all levels of biological and social organisation. Yet the existence and maintenance of cooperation is puzzling from an evolutionary perspective because the costs borne to cooperating individuals put them at an evolutionary disadvantage. We thus require an understanding of mechanisms and institutions that can enable cooperation to thrive and be maintained. In this dissertation, I discuss three issues that have presented, or currently present, a challenge to the sustenance of human cooperation. Chapter 2 addresses an issue of much contemporary debate – inequality. I ask how the well-documented, widespread lack of knowledge of income inequality in society affects the use of costly punishment and costly reward in maintaining public cooperation. When income inequality in a group is not known, the poorest group members are punished (for their low absolute contributions) while the richest are rewarded (for their high absolute contributions). Conversely, when income inequality is revealed, this outcome reverses: the poorest are rewarded (for their high percentage of income contributed) and the richest are punished (for their low percentage contributed). In Chapter 3, I turn to study the emergence of large-scale cooperation. How can cooperation arise and remain stable in large groups? Although it has been argued that the standard reciprocity mechanism weakens in large groups, a simple, scalable intervention—dubbed “local-to-global” reciprocity—successfully maintains public cooperation in groups orders of magnitude larger than previously studied. Local-to-global reciprocity works to maintain group-level cooperation because individuals withhold cooperation from defectors in pairwise interactions as a form of punishment. In Chapter 4, I investigate how we can cooperate with future generations: people today face the challenge that they must pay the cost of cooperation now to benefit people in the future who cannot reciprocate their actions. When people decide individually, the renewable resource quickly depletes leaving future generations empty-handed. When decisions today are made by majority vote, however, the resource is sustained for many generations. Voting works because it allows a cooperative majority to restrain a minority of present-day defectors.